gob

Introduction#

Gob is a Go specific serialisation method. it has support for all Go data types except for channels and functions. Gob also encodes the type information into the serialised form, what makes it different from say XML is that it is much more efficient.

The inclusion of type information makes encoding and decoding fairly robust to differences between encoder and decoder.

How to encode data and write to file with gob?

package main

import (
    "encoding/gob"
    "os"
)

type User struct {
    Username string
    Password string
}

func main() {

    user := User{
        "zola",
        "supersecretpassword",
    }

    file, _ := os.Create("user.gob")

    defer file.Close()

    encoder := gob.NewEncoder(file)

    encoder.Encode(user)

}

How to read data from file and decode with go?

package main

import (
    "encoding/gob"
    "fmt"
    "os"
)

type User struct {
    Username string
    Password string
}

func main() {

    user := User{}

    file, _ := os.Open("user.gob")

    defer file.Close()

    decoder := gob.NewDecoder(file)

    decoder.Decode(&user)

    fmt.Println(user)

}

How to encode an interface with gob?

package main

import (
    "encoding/gob"
    "fmt"
    "os"
)

type User struct {
    Username string
    Password string
}

type Admin struct {
    Username string
    Password string
    IsAdmin  bool
}

type Deleter interface {
    Delete()
}

func (u User) Delete() {
    fmt.Println("User ==> Delete()")
}

func (a Admin) Delete() {
    fmt.Println("Admin ==> Delete()")
}

func main() {

    user := User{
        "zola",
        "supersecretpassword",
    }

    admin := Admin{
        "john",
        "supersecretpassword",
        true,
    }

    file, _ := os.Create("user.gob")

    adminFile, _ := os.Create("admin.gob")

    defer file.Close()

    defer adminFile.Close()

    gob.Register(User{}) // registering the type allows us to encode it

    gob.Register(Admin{}) // registering the type allows us to encode it

    encoder := gob.NewEncoder(file)

    adminEncoder := gob.NewEncoder(adminFile)

    InterfaceEncode(encoder, user)

    InterfaceEncode(adminEncoder, admin)

}

func InterfaceEncode(encoder *gob.Encoder, d Deleter) {

    if err := encoder.Encode(&d); err != nil {
        fmt.Println(err)
    }

}

How to decode an interface with gob?

package main

import (
    "encoding/gob"
    "fmt"
    "log"
    "os"
)

type User struct {
    Username string
    Password string
}

type Admin struct {
    Username string
    Password string
    IsAdmin  bool
}

type Deleter interface {
    Delete()
}

func (u User) Delete() {
    fmt.Println("User ==> Delete()")
}

func (a Admin) Delete() {
    fmt.Println("Admin ==> Delete()")
}

func main() {

    file, _ := os.Open("user.gob")

    adminFile, _ := os.Open("admin.gob")

    defer file.Close()

    defer adminFile.Close()

    gob.Register(User{}) // registering the type allows us to encode it

    gob.Register(Admin{}) // registering the type allows us to encode it

    var admin Deleter

    var user Deleter

    userDecoder := gob.NewDecoder(file)

    adminDecoder := gob.NewDecoder(adminFile)

    user = InterfaceDecode(userDecoder)

    admin = InterfaceDecode(adminDecoder)

    fmt.Println(user)

    fmt.Println(admin)

}

func InterfaceDecode(decoder *gob.Decoder) Deleter {

    var d Deleter

    if err := decoder.Decode(&d); err != nil {
        log.Fatal(err)
    }

    return d

}